The main aim of the European Organization for Research and Treatment of Cancer (EORTC) is to conduct, develop, coordinate and stimulate research in Europe on the experimental and clinical bases of cancer treatment with the final goal being not only a reduction in the mortality rate of cancer patients, but also an improvement m their quality of life. The main work of the EORTC Treatment Branch is to conduct phase II and phase III trials which are carried out by the Clinical Cooperative Groups. The objectives of the EORTC Data Center are to provide state of the art support to the EORTC Clinical Cooperative Groups with respect to data management, computer, statistical and medical expertise at a central and hence economical site. Its goal is to provide and to ensure, from an independent, objective, academic point of view, the highest possible quality of the trial, from its design to the final analysis and publication of the final results, thus leading to an improvement in cancer treatment. While the EORTC Data Center is concerned with all aspects of the 200 trials carried out under its auspices, during the past 3 years increasing attention and Data Center support has been given to new areas such as meta-analysis, quality of life, cost effectiveness, cancer in the elderly, MDS related tumors, rare tumors, and fungal infections in cancer patients. In particular, an assessment of the economical aspects of cancer treatment in Europe is being undertaken and all new phase III trials will include, when appropriate, quality of life and health economics evaluations. Training and education, quality control and dissemination of information resulting from clinical research are of growing importance from the standpoint of encouraging state of the art treatment for an increasing proportion of cancer patients as is cooperation with other cancer research organizations. The aim of this competing continuation grant application is to request continuation of the support that the EORTC Data Center has received without interruption since 1974 so that it can pursue, reinforce and expand the range of services which it offers to the well established network of investigators participating in the EORTC Clinical Cooperative Groups.